Group B streptococcal PCR testing in comparison to culture for diagnosis of late onset bacteraemia and meningitis in infants aged 7–90 days: a multi-centre diagnostic accuracy study

Abstract

The aim of this study was to compare an in-house real-time PCR assay, with bacterial culture as the reference, for the diagnosis of late onset group B Streptococcal (GBS) disease. This was a retrospective review. All children aged 7-90 days presenting to four paediatric centres that had a blood or CSF sample tested by GBS PCR were included. Of 7,686 blood and 2,495 cerebrospinal fluid (CSF) samples from patients of all ages received for PCR testing, 893 and 859 samples were eligible for the study, respectively. When compared to culture, the sensitivity of blood PCR was 65% (13/20) in comparison to the CSF PCR test which was 100% (5/5). Ten of 23 PCR-positive blood samples and 17 of 22 PCR-positive CSF samples were culture negative. The median threshold Ct values for culture-positive/PCR-positive CSF samples was lower than that of culture-negative/PCR-positive CSF samples (p = 0.08). Clinical details of 17 available cases that were culture negative/PCR positive were reviewed; seven were deemed to be definite cases, eight were probable and two were possible. The results showed that detection of GBS by PCR is useful for CSF samples from infants aged 7-90 days with suspected meningitis; however, analysis of blood samples by PCR is of limited value as a routine screening test for late onset GBS sepsis and should not replace bacterial culture.

Towards accurate exclusion of neonatal bacterial meningitis: a feasibility study of a novel 16S rDNA PCR assay.

“…For example, the NeonIn network reported only 41 positive CSF cultures in the period from 2005 to 2014 [27]: a rate of around 0.1 per 1000 live births, which possibly underestimates the incidence by as much as 50% [12][13][14]. Similarly, in a recent large multicenter study in Ireland, bacterial CSF culture missed seven cases of definite Group B Streptococcal meningitis out of 12 [6]. For these reasons, in many babies bacterial meningitis cannot be promptly confirmed or ruled out with confidence.…”

Towards accurate exclusion of neonatal bacterial meningitis: a feasibility study of a novel 16S rDNA PCR assay.

“…For example, the NeonIn network reported only 41 positive CSF cultures in the period from 2005 to 2014 [27]: a rate of around 0.1 per 1000 live births, which possibly underestimates the incidence by as much as 50% [12][13][14]. Similarly, in a recent large multicenter study in Ireland, bacterial CSF culture missed seven cases of de nite Group B Streptococcal meningitis out of 12 [6]. For these reasons, in many babies bacterial meningitis cannot be promptly con rmed or ruled out with con dence.…”

“…Based on 16S rDNA PCR technology, PCRctic can detect virtually any type of bacterium. Through elimination of free bacterial DNA it can fully realize its sensitivity and detect single numbers of intact bacteria in the specimen -just as a well-designed bacterium-speci c PCR can [6,50]. These two features produce an ideal format for accurate identi cation of bacteria-free specimens.…”

“…The clinical signs of neonatal meningitis are very non-speci c [1] and the current UK practice is to test cerebro-spinal uid (CSF) for meningitis in all newborn babies with suspected sepsis and raised Creactive protein [2]. With many babies exposed to antibiotics intrapartum [3] and with nearly all babies receiving antibiotics before the lumbar puncture [2], a negative result in CSF bacterial culture does not rule out bacterial meningitis [4][5][6]. CSF pleocytosis can be indicative of meningitis, but CSF microscopy can be di cult to interpret: (i) up to 50% of neonatal lumbar punctures result in blood-stained CSF [7,8], (ii) there is uncertainty as to what constitutes a normal CSF white cell count in healthy babies [9,10], and (iii) "normal" CSF microscopy does not exclude bacterial meningitis [11].…”

Neonatal Meningitis: Overcoming Challenges in Diagnosis, Prognosis, and Treatment with Omics

“…Nonetheless, additional testing is required to determine the reliability of CSF PCR tests when compared with culture results in the management of bacterial meningitis in the clinical setting. To date, bacterial tests of sources other than CSF have shown disappointingly poor accuracy in diagnosis of meningitis (32). …”